Abstract

bahl~microsoft, corn ymwang~microsoft, corn rogerwa~microsoft, corn The topology of a wireless multi-hop network can be con-trolled by varying the transmission power at each node. In this paper, we give a detailed analysis of a cone-based dis-tributed topology control algorithm. This algorithm, intro-duced in [16], does not assume that nodes have GPS in-formation available; rather it depends only on directional information. Roughly speaking, the basic idea of the algo-rithm is that a node u transmits with the minimum power P~,,a required to ensure that in every cone of degree a around u, there is some node that u can reach with power Pma- We show that taking a = 57r/6 is a necessary and sufficient con-dition to guarantee that network connectivity is preserved. More precisely, if there is a path from a to t when every node communicates at maximum power then, if a < _ 5~r/6, there is still a path in the smallest symmetric graph Ga con-taining all edges (u, v) such that u can communicate with v using power p~,a. On the other hand, if ~> 51r/6, connec-tivity is not necessarily preserved. We also propose a set of optimizations that further reduce power consumption and prove that they retain network connectivity. Dynamic re-configuration in the presence of failures and mobility is also discussed. Simulation results are presented to demonstrate the effectiveness of the algorithm and the optimizations. 1.

Citations